Carboxylic acids continued structure

The nomenclature for this homologous series is somewhat confused. The term PANs has been used historically to denote peroxyacyl nitrates, and this terminology continues to be used extensively in the literature, despite the lack of adherence to traditional IUPAC rules of nomenclature. Because the PANs can be considered to be mixed anhydrides of carboxylic acids and nitric acid, another suggestion (Roberts, 1990) has been peroxyacetic nitric anhydride for CH,C(0)00NO2 and peroxy carboxylic nitric anhydrides for the whole class of compounds. Although it does not follow the IUPAC rules, it would be consistent with the widespread use of the name PAN but also reflect the structure more accurately. Table 6.20 shows the structures and commonly used names of some PANs that have been observed in the atmosphere and/or in laboratory studies. 

Reduction then proceeds by successive transfers of hydride ion, H e, from aluminum to carbon. The first such transfer reduces the acid salt to the oxidation level of the aldehyde reduction does not stop at this point, however, but continues rapidly to the alcohol. Insufficient information is available to permit very specific structures to be written for the intermediates in the lithium aluminum hydride reduction of carboxylic acids. However, the product is a complex aluminum alkoxide, from which the alcohol is freed by hydrolysis ... 

Rh(II) carboxylates, especially Rh2(OAc)4> have emerged as the most generally effective catalysts for metal carbene transformations [7-10] and thus interest continues in the design and development of dirhodium(II) complexes that possess chiral51igands. They are structurally well-defined, with D2h symmetry [51] and axial coordination sites at which carbene formation occurs in reactions with diazo compounds. With chiral dirhodium(II) carboxylates the asymmetric center is located relatively far from the carbene center in the metal carbene intermediate. The first of these to be reported with applications to cyclopropanation reactions was developed by Brunner [52], who prepared 13 chiral dirhodium(II) tetrakis(car-boxylate) derivatives (16) from enantiomerically pure carboxylic acids RlR2R3CC OOH with substituents that were varied from H, Me, and Ph to OH, NHAc, and CF3. However, reactions performed between ethyl diazoacetate and styrene yielded cyclopropane products whose enantiopurities were less than 12% ee, a situation analogous to that encountered by Nozaki [2] in the first applications of chiral Schiff base-Cu(II) catalysts. 

The structure of the epoxy-dialdehyde (15), from Afromomum daniellii (Zingiberaceae), was established by correlation with c -12-norambreinolide. The hydroxy-acid (16), salvic acid from Eupatorium salvia,and the ring B seco-labdane jhanic acid (17) from Eupatorium jhanii are two further diterpenoids from these species of the Compositae. The structure of the latter rests on interpretation of the H and C n.m.r. data. Gutierrezia lucida (Compositae) contains the 13-epimeric acids (18) related to agathic acid together with the butenolide (19). Some esters of 6-hydroxylabdane-17-carboxylic acids were detected in G. mandonii. The investigation of Cistus species has continued. The ent-labdane acetyl-laurifolic acid (20) is a component of Cistus laurifolius ... 

Decarbonylations of furfuraldehyde to furan continue to be of commercial interest and various new catalysts have been recommended.253 Decarboxylations are still occasionally useful,254 and the selective decarboxylation of furan-3,4-dicarboxylic acid to furan-3-carboxylic acid is said to be much improved by omitting any solvent.255 The easy decarboxylation of furan acetic acid derivatives is formulated in structure 139, although the acidic conditions need not preclude ring opening.2553... 

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